“We want the free world to stop the onslaught on defenseless civilians,” said Mahmoud Ali of the Constitution Party, according to state-owned news agency MENA. “We want to relay to the steadfast Palestinian people the support of all Egyptians.”

“We brought them medical supplies in coordination with the Egyptian Red Crescent,” said activist Amira Sheaishaa.

A five-bus convoy transporting members of several Egyptian parties and political movements arrived at the country's Rafah border crossing with Gaza, officials said.

"We all entered through Rafah border ... 100s now attempting to enter Gaza," activist Gigi Ibrahim said on her Twitter account, according to AFP.

Israeli air strikes on Sunday killed at least 21 Palestinians in the bloodiest day of its massive air campaign to halt rocket fire from the Gaza Strip.

Since the operation was launched on Wednesday, 67 Palestinians have been killed and more than 600 injured, while three Israelis have died and more than 50 have been injured by rocket fire.

Egypt is at the center of efforts to broker a ceasefire. Security officials in Cairo said an Israeli envoy also arrived in the Egyptian capital on Sunday for talks.

Under former President Hosni Mubarak, relief convoys were seldom allowed to cross into Gaza.

This article is an edited combination of an AFP wire story and a MENA story translated from Arabic